Why Would a Smoke Detector Go Off Without Smoke?

[Janus]

Okay, I'm at work and I get a phone call from my daughter. Our smoke detector had gone off for no apparent reason. Unfortunately, it is the type that runs off of house current and the only way to turn it off is to turn the breaker off. However, that breaker also supplies power to the whole kitchen. She had turned off the breaker to silence it, but wanted to know if there was any way to turn off just the detector.

I told her that the only way to do that was to disconnect it, and I didn't want here messing with wiring. I then told her to try turning the breaker back on to see if the detector had cleared itself. She did, and it seemed to work.

A little while later, I get a text from my wife, saying that they smelt a burnt electrical smell that seemed to come from the area of the detector. It seems that something in the detector itself had shorted or over-heated, and that was what set it off in the first place.

It looks like we'll be getting a new detector.

The one we have was put in by the previous landlord as an replacement, and I was never really happy with his decision to use a house current model. For one, he took out a hall light to wire it in, and second every time you burnt a piece of toast you had to shut the power off to the kitchen to silence it. And since he tied it into a circuit that is used by so many other things(most of them far removed form the detector), I'm not sure how safe it is. An appliance could short out in the kitchen starting a fire while at the same time tripping the breaker before the smoke has a chance to reach the smoke detector.

I'm going to ask the new landlord to replace it with a battery powered one. (And I'm going to put the hall light back in; we still have the fixture.)

 

[Evo]

They don't have a reset button? In this and my last place, the alarms work on household electricity and have a backup battery.

Last time the problem was a low battery, so it wouldn't reset, I had to remove the battery to turn it off.

 

[Office_Shredder]

The smoke detector makes a noise because the battery is low. It wouldn't turn off because that's what it's supposed to do

 

[schip666!]

It doesn't have a battery backup? Bad detector...no more smoke.

I find waving a hand towel under the detector usually makes minor toast-alarms dissipate, w/o resorting to powering-down the entire kitchen. Of course my housemate manged to destroy a nice ceramic casting I got from Los Alamos surplus while performing this maneuver, so caution is advised.

I recent read that photoelectric detectors are preferred for home use over the ionization types because they are better suited to detecting smoldering fires, which are more often the culprits in a residence. A brief description is here: http://chemistry.about.com/cs/howthingswork/a/aa071401a.htm

 

[Evo]

The smoke detector makes a noise because the battery is low. It wouldn't turn off because that's what it's supposed to do

Except if you remove the battery the noise stops, but the alarm still works on electricity, not you have no back up.

My point though was that there should be a reset button on Janus' alarm. I usually use the tip of a broom handle to do the job.

 

[Janus]

Yeah, I think my last landlord just went the cheapest route possible. The only button was the "test" button, and no battery back-up.

Anyway, the landlord called after I got home from work to find out how things were going. (My wife had called her earlier in the day) I had had a chance to look at the detector and determine that it was toast, so I told her so. I also told here that I would prefer a battery type for a replacement and that If it was alright with her, I'd pick one up myself and just take the cost off of next months rent. It was fine with her and said that if I could find it, to get one that also detected carbon monoxide, as by April of next year the law required a CO detector to be installed.

I ran off to Home Depot picked one up. I got it home and put the batteries in. Instead of beeping once, flashing the red light for 20-30 sec and blinking the green light, like it was supposed to, it started to flash the red light while constantly chirping at me. After a minute I decided that it wasn't going to stop. I checked to see that batteries were in right and then switched them out for a new set. Same thing. It obviously wasn't working right.

Back to Home Depot. I exchanged it for a new one and had them open the package of the new one so I could put the batteries in and make sure it worked before I left, which it did. It's now installed, and my family is protected once again.

Its a much better unit. Voice alert that tells you what it is detecting, A memory that tells you if the CO levels went too high even if you weren't there to hear it go off, and a hush button that temporarily silences the smoke alarm unless the smoke levels rise.

 

[Ivan Seeking]

Yeah, I think my last landlord just went the cheapest route possible. The only button was the "test" button, and no battery back-up.

I don't see why you're complaining. It worked!

 

[dlgoff]

I'm wondering about the CO detector part and it's location. Isn't CO heavier than air and wouldn't it build up from the floor up? If so, and your detector is located on the ceiling, would you be able to hear it by the time the gas got to the detector?

 

[Office_Shredder]

dlgoff, you're thinking about carbon dioxide